Dr. Alfred G. Redfield performs a simplified Millikan experiment photographed through the microscope. Substituting standard spheres for oil drops, he demonstrates the effect of X-rays and the relationship of the charge to the velocity of the spheres. Professor Francis L. Friedman explains that charge comes in natural units that are all alike, and points out numerous changes of charge. For more info on PSSC, its history, and films, visit http://www.afana.org/psscfilms.htm